Nowadays, there are more and more metal elements applied in mobile phones, and an all-metal housing has gradually become mainstream of the appearance of the mobile phones. However, with the increase of metal, clearance of an antenna can be reduced, which affects outward radiation and signal reception of the antenna. Therefore, this brings challenge for the design of the antenna.
In view of the performance of a single antenna, the greater the clearance is and the less the metal in surrounding environment of the antenna is, the better the performance is. Therefore, for a mobile phone with a metal frame, if the frame is able to be used as a part of the antenna to radiate, better performance can be achieved.
For a conventional LTE antenna, operating frequency thereof needs to cover a full frequency band of 700 MHz to 2690 MHz. In general, even using the metal frame of the mobile phone as a part of the antenna to radiate, bandwidth is still very limited, in particular, the effect of using uncommon low frequency band at present is relatively poor, therefore, lines still need to be additionally disposed in other places inside the mobile phone to meet the required frequency band for covering. However, these additional disposed lines can only be arranged in a non-frame region, and thus the efficiency of the resulting resonant frequency is relatively poor.